As the trend and target of the next generation digital communication technology innovation and development, the 3rd-Generation Partnership Project (3GPP) is one of the hotspots in the world currently. The 3GPP network structure basically comprises the circuit switched (CS) domain and the packet switched (PS) domain. FIG. 1 is a schematic view of the network structure of the 3GPP communication system in the conventional art. The network structure is similar to the second generation mobile communication system, and comprises the Universal Terrestrial Radio Access Network (UTRAN), GSM/EDGE Radio Access Network (GERAN), core network (CN) and user equipments (UEs). The GERAN/UTRAN is adapted to implement all radio-related functions, while the CN processes all the voice calls and data connections in the General Packet Radio Service/Universal Mobile Telecommunication Service (GPRS/UMTS) system, and to implement the functions of handover and routing with external networks. Logically, the CN is classified into the CS domain supporting voice services and the PS domain supporting data services. The CS domain comprises nodes such as the Mobile Switching Center Server (MSC-Server), Media Gateway (MGW) and Gateway Mobile Switching Center Server (GMSC-Server). The MSC-Server is adapted to transmit control plane data of the CS domain, and to implement the functions of mobility management, call control, authentication and encryption and the like. The GMSC-Server is adapted to implement the control plane functions of call control and mobility control of the GMSC. The MGW is adapted to implement the transmission of the user plane data. The PS domain comprises nodes such as the Serving GPRS Supporting Node (SGSN) and the Gateway GPRS Supporting Node (GGSN). The GGSN is adapted to interface with the external network, and to implement the transmission of the user plane data. The location of the SGSN in the PS domain is similar to the location of the MSC-Server in the CS domain, and the core functions of the SGSN is to implement the functions of routing and forwarding, mobility management, session management and user information storage, etc. The Home Location Register (HLR) is adapted to store the user subscription information, and the CS and PS domains both use the HLR.
FIG. 2 is a schematic view of the policy and charging control (PCC) network structure of the 3GPP system. The PCC system network comprises logic entities such as the Application Function (AF), the Policy and Charging Rules Function (PCRF), the Subscription Profile Repository (SPR), the Policy and Charging Enforcement Function (PREF), the Online Charging System (OCS), the Offline Charging System (OFCS), and the Gateway (GW). The AF is a network element providing applications that require dynamic policy control. The PCRF mainly performs the policy control decision and stream charging control function. The SPR is adapted to store the PCC-related subscription data needed by the PCRF. The PCEF mainly provides the service data stream detecting, policy enforcement and stream charging functions, which is a function entity located on the gateway device. The OCS is responsible for the online charging function. The OFCS is responsible for the offline charging function.
In order to enhance the competitiveness of the future network, the 3GPP is researching on a new evolution network architecture, comprising the System Architecture Evolution (SAE) and the Long Term Evolution (LTE) of the access network. The evolved access network is referred to as E-UTRAN, and the evolved packet core network architecture is as shown in FIG. 3, comprising logical function entities such as the Mobility Management Entity (MME), the User Plane Entity (UPE) and the Inter Access System Anchor (IASA). The MME is responsible for mobility management of the control plane, comprising the user context and mobile state management, and is responsible for allocating temporary user identities, which is corresponding to the control plane part of the internal SGSN of the current GPRS/UMTS system. The UPE is responsible for initiating paging for downlink data in the idle state, and managing and storing IP bearer parameters and internal network routing information, which is corresponding to the data plane part of the internal SGSN and GGSN of the current GPRS/UMTS system. The IASA acts as the user plane anchor between different access systems. The 3GPP Anchor logical function entity is the user plane anchor between the 2G/3G access system and the LTE access system. The SAE Anchor logical function entity is the user plane anchor between the 3GPP access system and the non-3GPP access system. The PCRF is responsible for policy control decision and stream charging control function. The Home Subscriber Server (HSS) is adapted to store the user subscription information.
Referring to FIG. 4, the process for the handover from the GERAN/UTRAN system to the SAE/LTE system under the MME/UPE separation architecture in the conventional art comprises the following steps.
In step 1, the IP bearer service is established between the UE, the 2G/3G access system, the 2G/3G SGSN and the SAE UPE/IASA.
In step 2, the 2G/3G access system decides to initiate a handover process to hand over to the LTE access system (Handover Initiation).
In step 3, the 2G/3G access system decides to initiate a handover request message to the 2G/3G SGSN (Handover Required). The 2G/3G SGSN selects an MME to process the handover.
In step 4, the 2G/3G SGSN sends a handover preparation request message comprising the UE context information to the selected MME. The MME creates the UE context and sends the handover preparation request message to the LTE access system (Handover Preparation Request).
In step 5, the LTE access system reserves the user plane resources after receiving the handover preparation message sent by the MME, and establishes the radio bearer (LTE access reserves UP resources).
In step 6, the LTE access system sends a handover preparation confirm message to the MME, and the MME sends the handover preparation confirm message to the 2G/3G SGSN (Handover Preparation Confirm).
In step 7, the 2G/3G SGSN initiates a handover command to the UE (Handover Command).
In step 8, Means to minimize loss of data, such as data forwarding or bi-casting process, is performed. The lossless data processing is not the content of the present disclosure, and will not be described here.
In step 9, the LTE access system detects the UE (UE Detection).
In step 10, the LTE access system sends a handover complete message to the MME, and the MME sends the handover complete message to the 2G/3G SGSN (Handover Complete).
In step 11, the 2G/3G SGSN sends a handover complete acknowledgement message to the MME (Handover Complete Ack).
In step 12, the route from the UPE/IASA user plane to the LTE access system is established (User Plane route update).
In step 13, the source 2G/3G access system releases the resources (Resource Release).
In step 14, the IP bearer service is established between the UE, the LTE access system and the UPE/IASA.
During researches and applications, the inventors find a problem in the process described above, that is, multiple SAE bearers in the existing SAE system share the Quality of Service (QoS) parameters such as the Aggregate Maximum Bit Rate (AMBR). These SAE bearers have no separate QoS parameters such as the Maximum Bit Rate (MBR) in the LTE access system. In the current 2G/3G access systems, the bearers all use separate QoS parameters such as the MBR, but no bear shares QoS parameters such as the MBR, and the current 2G/3G subscription data has no QoS parameters such as the AMBR. Thus, during the handover from the 2G/3G system to the SAE system, the SAE system cannot determine QoS parameters such as the AMBR when establishing the bearer.